1. Field of the Invention
The present invention is related to medical devices. More particularly, the present invention is related to a syringe device for mixing and delivering liquid medications.
2. Background
It is desirable in many clinical situations to selectively occlude or embolize blood vessels for a variety of purposes, such as, the control or prevention of bleeding (e.g., organ bleeding, gastrointestinal bleeding, vascular bleeding, bleeding associated with an aneurysm). Embolization of blood vessels has been performed by employing certain polymer suspensions and particulates including silicone, metallic coils, sclerosing materials and the like to selectively block blood flow in the blood vessels.
One minimally invasive procedure for treating aneurysms, for example, involves the endovascular injection, via a syringe or catheter device, of a liquid embolic composition which accumulates in the aneurysm to occlude the aneurysm. The liquid embolic composition preferably comprises an aqueous vehicle, a biocompatible polymer and a water soluble contrast agent. The aqueous vehicle is miscible or soluble in blood or other body fluid and also carries the biocompatible polymer for the short period of time between their being brought together in a syringe, and the moment of delivery. The biocompatible polymer is selected to be suspensible in the aqueous vehicle by virtue of constantly being agitated, up until the time of injection. The water soluble contrast agent is mixed with the composition and permits the physician to fluoroscopically visualize catheter delivery of this composition.
Once the liquid embolic composition is injected into the aneurysm, the biocompatible polymer aggregates due to lack of turbulence and forms an embolic occlusion within the blood vessel, occluding the blood flow through the aneurysm.
A problem may arise, however, if the embolic composition accumulates within the syringe or catheter before delivery. Specifically, it has been found that the catheter line can become plugged due to premature aggregation of the biocompatible polymer. This plugging, of course, interferes with delivery of the composition to the specific site in vivo.
To prevent premature aggregation of the embolic particles within the composition and maintain uniform suspension, the composition should be mixed and agitated, before delivery. In general, a syringe device for agitating and delivering a liquid embolic composition to a vascular site comprises a larger syringe and a smaller high pressure syringe coupled together at their dispensing ends. The larger syringe provides the composition to the smaller syringe and the composition is passed back and forth to agitate the composition and maintain a uniform suspension of the embolic particles within the composition. The composition is passed back and forth by advancing and retracting the corresponding plungers. A disadvantage to using this type of syringe device is that its operation requires the operator to use two hands to manipulate the corresponding plungers of the two syringes, i.e., one hand for each plunger/syringe.
Thus, there is a need to provide an improved syringe device particularly useful for avoiding premature precipitation of a liquid embolic composition.